Automated methods of searching databases are generally known. For example, P. G. Ossorio developed a technique for automatically measuring the subject matter relevance of documents (Ossorio, 1964, 1966, 1968, 1969). The Ossorio technique produced a quantitative measure of the relevance of the text with regard to each of a set of distinct subject matter fields. These numbers provided by the quantitative measure are the profile or information spectrum of the text. H. J. Jeffrey produced a working automatic document retrieval system using Ossorio's technique (Jeffrey, 1975, 1991). The work by Ossorio and Jeffrey showed that the technique can be used to calculate the information spectra of documents, and of requests for information, and that the spectra can be effective in retrieving documents.
However, Ossorio's technique was designed to solve a particular kind of document retrieval problem (i.e., fully automatic retrieval with complete cross-indexing). As a result, the technique has certain characteristics that make it unusable for information retrieval in cases in which there is a very wide range of subject matter fields, such as the Internet.